Technical Articles

Winter Notes and Precautions Bulletin

RE: Winter notes and precautions bulletin

Valued Noritz Customer,

Winter is coming upon us and we would like to ensure that you and your family will be able to en joy your endless hot water during this colder season. Please read through this bulletin and follow any recommendations that may apply to your installation.

(Note: The following suggested procedures are intended to reduce the likelihood of freezing due to severe weather, but they are not a complete solution for all situations. Repairs for damage caused by freezing are not covered by the warranty.)

Are you going to be away from your heater for an extended period of time? Be sure to properly winterize your tankless water heater!

Please follow "Preventing damage from freezing” steps as outlined in the owners guide, which can be found at

Are you in an area in which outside temperatures fall below 35°F (0°C) and/or power outages may occur?

Current Noritz models have internal freeze prevention rating of -30°F (indoor installation) and -4°F (outdoor installation), the exception being the NC380 series, which has an indoor and outdoor freeze rating of -4°F.   

Freezing cannot be prevented when the power plug is unplugged. Do not remove the power plug from the wall outlet or disconnect electrical power to the unit. The freeze prevention heaters will not prevent the plumbing external to the unit from freezing. Protect this plumbing with insulation, heat tape, electric heaters, solenoids, and/or pipe covers.

If you are in an area that is prone to freezing temperatures and power outages are an issue, we highly recommend having a back up electrical source to provide power to the freeze prevention heaters. Uninterruptible power supplies (UPS) and gas powered generators are two commonly used electrical back up supplies. If using back up power supplies, it is important that the electrical signal produces a pure-sine wave output. More info can be found at under the FAQ section.

For extremely cold temperatures, we recommend taking the measures below :

Please follow "Preventing damage from freezing” steps as outlined in the owners guide, located at

Will you have multiple gas appliances running during the winter season? Verify that you have adequate gas for all appliances on meter.

During the winter season, it is common to encounter error codes such as 11, 12, 59, and 90. These codes typically appear due to lack of gas being supplied to the unit and will be most noticeable during the winter season. If a new gas meter was not installed during the installation of your tankless water heater, we recommend verifying that your gas meter is properly sized for all your gas appliances. To do this, add all gas appliance Btuh demands (tankless heater, furnace, gas range, fireplace, dryer, etc.) and compare to gas meter size. If the meter is sized for less than all appliances, we recommend contacting your gas company.

Do you have a recirculation plumbing system?

During extreme cold temperatures, we recommend running your recirculationpump more frequently, especially during the colder hours. This is will keep your tankless heater and water pipes warm lessening the likelihood of freeze issues. If you know there will be a freeze, make sure the recirculationpump and unit will be operating during the freeze.

Additional Freeze Prevention Information:

In regions of excessive cold weather it may be necessary to employ additional methods (other than those outlined above) to protect against freeze damage. The following sections give suggested design improvements with regards to venting, installation environment, and additional equipment.


When designing your venting for an extreme climate keep in mind the following suggestions:

·Longer vent runs (longer than three feet) and multiple elbows provide a greater protection from freezing.

·Vertical vent runs provide superior back draft prevention when compared to horizontal vent runs; use a vertical vent run whenever possible.

·When installing a DVC unit use Noritz approved terminations only.

·Take care to locate horizontal terminations so they face away from prevailing winds.

·When venting to the side wall use wind resistant terminations (i.e. "T"-type or box terminations).

Installation Environment:

In areas with extreme weather conditions, units should be installed in a heated space. If this is not possible units should be installed on walls adjacent to a heated space rather than a wall exposed to the elements.

Additional Equipment:

The following equipment could help to prevent freezing:

·Water pipe insulation helps to prevent water lines from freezing below the unit and damaging internal components.

·Heat Tape/Traceruses a resistive heating element to heat the water piping and prevent it from freezing.

·Drain Down Solenoids allow water to partially drain from the system in the event of a power outage.

·Pipe covers/recess boxescan be used to add additional protection from the elements.

For information on any other technical related issues, please visit



Applicable Models
  • Models: ALL MODELS
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